XB-ART-11393Development 2000 Apr 01;1277:1455-65. doi: 10.1242/dev.127.7.1455.
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HNF1(beta) is required for mesoderm induction in the Xenopus embryo.
XHNF1(&bgr;) is a homeobox-containing gene initially expressed at the blastula stage in the vegetal part of the Xenopus embryo. We investigated its early role by functional ablation, through mRNA injection of an XHNF1(beta)/engrailed repressor fusion construct (XHNF1(beta)/EngR). Dorsal injections of XHNF1(beta)/EngR mRNA abolish dorsal mesoderm formation, leading to axial deficiencies; ventral injections disrupt ventral mesoderm formation without affecting axial development. XHNF1(beta)/EngR phenotypic effects specifically depend on the DNA-binding activity of its homeodomain and are fully rescued by coinjection of XHNF1(beta) mRNA. Vegetal injection of XHNF1(beta)/EngR mRNA blocks the mesoderm-inducing ability of vegetal explants. Both B-Vg1 and VegT maternal determinants trigger XHNF1(beta) expression in animal caps. XHNF1(beta)/EngR mRNA blocks B-Vg1-mediated, but not by eFGF-mediated, mesoderm induction in animals caps. However, wild-type XHNF1(beta) mRNA does not trigger Xbra expression in animal caps. We conclude that XHNF1(beta) function is essential, though not sufficient, for mesoderm induction in the Xenopus embryo.
PubMed ID: 10704391
Article link: Development
Species referenced: Xenopus
Genes referenced: chrd.1 fgf4 gdf1 gsc hnf1a hnf1b nodal3.2 not post tbxt vegt ventx2.1 xpo1
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|Fig. 2. Expression of XHNF1 beta;. (A) Developmental RT-PCR analysis of XHNF1 beta; expression. Xenopus embryonal stages are indicated in the upper part of the panel. Ornithine decarboxylase (ODC) was used as an internal control. (B,C,D,G,H) XHNF1beta; expression as detected by whole-mount in situ hybridization at blastula stage 8.5 (B) and stage 9 (C), gastrula stage 10.25 (D), neurula stage 14 (G) and tailbud stage 29 (H); expression of Xbra (E) and chordin (F) at gastrula stage are shown for comparison. Arrowheads indicate the embryo marginal zone (B), or the dorsal blastopore lip (D); arrows in G and H point towards XHNF1β expression in neuroectoderm and pronephric system, respectively.|
|Fig. 5. Molecular marker analysis of XHNF1 beta/EngR mRNA-injected embryos. As indicated, embryos were bilaterally injected at 4-cell stage either dorsally (4C/2D), or ventrally (4C/2V), and processed for in situ hybridization with probes for goosecoid (gsc), chordin (chd), Xnot2, Xnr3, Xwnt-8, Xbra, Xpo and Xvent-2,. Analysis was performed either at early neurula stage 12.5 (A-F; A,D-F, dorsal views; B,C, posterior views), or at gastrula stage 10.25-10.5 (G-T; vegetal view). Control embryos (wt) are also shown. Note absence of dorsal blastopore lip in B and C.|